In polymer chemistry, polyols are compounds with multiple hydroxyl functional groups available for chemical reactions. A major use of polyols is as a reactant to make polymers. Polyols may also be used for other purposes including in cosmetic formulations, lubricants and as chemical intermediates. Polyols themselves may be monomeric, oligomeric or polymeric. The ability to produce polyols of different molecular weights is desirable since these can be used to produce polymer networks with different properties. Monomeric or oligomeric polyols may be polymerized, for example into polyesters or polyethers, before conversion to other polymers such as polyurethanes.
Polyol production from renewable, non-petroleum based sources is desirable from a sustainability perspective. Methods are known for the preparation of polyols from vegetable oil, typically involving harsh reaction conditions that are not easily controlled, and using expensive starting materials and catalysts. Natural oils or fatty acids may be oxidized by ozonolysis, or epoxidized with peroxy acids, followed by hydroxylation to produce polyols.
A process for preparing polyol from fatty acid substrates such as free fatty acids, alkyl esters of fatty acids, mono-glycerides, diglycerides, and triglycerides is disclosed in United States Patent Application Publication No. 2013/0274494. The process involves epoxidizing the fatty acid substrate and then hydroxylating the epoxidized unsaturated substrate with at least one diol to produce a polyol or a blend of polyols. While the epoxidation of unsaturated oils proceeds well under optimized epoxidation conditions without loss of the epoxy groups, the epoxidation of the fatty acid methyl esters (FAMEs) and free fatty acids mixtures (FFAs) show extensive loss of epoxy groups (hence epoxy functionality) due to premature epoxy ring opening under acid attack and/or due to the oligomerization processes occurred during epoxidation.
Accordingly, there is a need in the art for improved or alternative processes of preparing polyols.